The USGS has a page with scientific information about the magnitude 6.0 earthquake that hit the Napa area this weekend. You may also want to use their “Did You Feel It?” service to report if you felt the earthquake; this helps build a “community intensity map” of impact.
If you want to know more about earthquakes in California in general, see the USGS California Earthquake page, and for library resources visit the Earthquakes section of the Geology Libguide to find databases for articles, reference works, and the contact information of the Geology librarian.
Professor John Rundle from Geology gave a TV interview on the history and the science of the quake, which you can see here.
